Sitting presidents rarely campaign strongly for a successor. According to NPR, Obama's open support for a Clinton presidency has not been matched by another president for at least a century. He spoke candidly to the Congressional Black Caucus about how he would consider it a "personal insult" to his legacy if Black Americans didn't turn out in large numbers to vote for Clinton over Trump, according to The Chicago Tribune.

"Can I just say I am really into electing Hillary Clinton?" CNN reported Obama asking the crowd at a Philadelphia rally. "This is not me just going through the motions here. I really, really, really want to elect Hillary Clinton."

Obama's approach to Trump is no less unprecedented than his support for Clinton. During an August appearance with the Singaporean Prime Minister, Obama called Trump "unfit" and "unprepared" to be president, based on what he called Trump's lack of basic knowledge of critical world issues. He even criticized top Republicans for continuing to support Trump, cautioning against handing over nuclear military power to him.

Third-party candidate Gary Johnson did not qualify for the debate, said the Commission on Presidential Debates. Johnson, the Libertarian Party nominee, is the strongest-polling candidate from a non-major party in 20 years, but he just missed the 15-percent polling cutoff to be eligible to debate. Green Party candidate Jill Stein's campaign is organizing a protest outside the debate, The Guardian reported. It's been rumored that protesters may risk arrest to attempt to "escort" Stein onto the debate stage. On the other hand, Johnson plans to keep campaigning in hopes of being allowed into a subsequent debate.

The first presidential debate will take place on September 26, the 56th anniversary of the first televised presidential debate between Richard Nixon and John F. Kennedy. It will be held at Hofstra University in Hempstead, NY from 9 p.m. to 10:30 p.m. ET.

The debate's topics have been announced as America's Direction, Achieving Prosperity, and Securing America. Two 15-minute segments will be devoted to each topic, for a total of six segments. The debate will be viewable on many platforms, most notably through live-streaming on social media websites, including Twitter and Facebook.